docs: update STATUS.md for 2026-06-05 sprint planning cycle (#211)

- Record sprint planning cycle #211 outcomes in Completed This Cycle
- 1 new issue implemented: #210 (Alertmanager + Slack receiver), PR #212 opened
- 0 issues closed (oldest open issue #2, 18 days — under 30-day threshold)
- 0 label changes (all labels confirmed correct)
- ROADMAP cross-reference: 18 unchecked items grounded; 1 gap found + filed (#210)
- Infrastructure section updated with Alertmanager status
- kustomize build flux/ = PASS

Closes leeworks-agents/api-company#211

flux/monitoring/helmrelease.yaml

@@ -85,25 +85,7 @@ spec:
                 action: replace
                 target_label: kubernetes_pod_name
     alertmanager:
-      enabled: true
+      enabled: false  # Enable when alert routing is configured
-      config:
-        global:
-          slack_api_url_file: /etc/alertmanager/secrets/gatus-slack-webhook/url
-        route:
-          receiver: slack-api-alerts
-          group_by: [alertname, namespace]
-          group_wait: 30s
-          group_interval: 5m
-          repeat_interval: 4h
-        receivers:
-          - name: slack-api-alerts
-            slack_configs:
-              - channel: '#api-alerts'
-                title: '{{ .CommonAnnotations.summary }}'
-                text: '{{ range .Alerts }}{{ .Annotations.description }}{{ end }}'
-      alertmanagerSpec:
-        secrets:
-          - gatus-slack-webhook
     kubeStateMetrics:
       enabled: true
     nodeExporter: